Experimental study on transient behavior of semi-open two-phase thermosyphon     

朱华  王建新  张巧惠  屠传经 《浙江大学学报(A卷英文版)》2004,5(12):1565-1569

An experimental system was set up to measure the temperature, pressure, heat transfer rate and mass flow rate in a semi-open two-phase thermosyphon. The behaviors of a semi-open two-phase thermosyphon during startup, shutdown and lack of water were studied to get complete understanding of its thermal characteristics. The variation of wall temperature, heat-exchange condition and pressure fluctuations of semi-open two-phase thermosyphons showed that the startup of SOTPT needs about 60～70 min; the startup speed of SOTPT is determined by the startup speed of the condensation section; the average pressure in the heat pipe is equal to the environmental pressure usually; the shutdown of SOTPT needs about 30～50 min; a semi-open two-phase thermosyphon has good response to lack of water accident.  相似文献   

A new photonic bandgap cover for a patch antenna with a photonic bandgap substrate     

林青春  朱方明  何赛灵 《浙江大学学报(A卷英文版)》2004,5(3):269-273

A new photonic bandgap (PBG) cover for a patch antenna with a photonic bandgap substrate is introduced. The plane wave expansion method and the FDTD method were used to calculate such an antenna system. Numerical results for the input return loss, radiation pattern, surface wave, and the directivity of the antennas are presented. A comparison between the conventional patch antenna and the new PBG antenna is given. It is shown that the new PBG cover is very efficient for improving the radiation directivity. The physical reasons for the improvement are also given. Project supported by the National Natural Science Foundation of China (No. 90101024) and the Science and Technologies of Zhejiang Provinc (No. ZD0002)  相似文献   

Teaching–research relations,cross-disciplinary collegiality and student learning     

Keith?TrigwellEmail author 《Higher Education》2005,49(3):235-254

University students experience of cross-disciplinary collegiality and interaction with research-active teachers are explored using the results from two separate, but related, studies. In the first study, variation in students understanding of collegiality and how it is experienced is investigated. The second (quantitative) study explores the relations between students perceptions of collegiality in their learning environment and their learning outcomes and satisfaction. Within the collegiate system of the University of Oxford, students describe collegiality as encompassing a sense of allegiance and as a set of interactions with important others. Interactions were common between students in one disciplinary area and those in other disciplines. They are also found between students in one subject and other students in the same discipline, in the same and a different year of study and, in terms of learning, most effectively between students and research-active teaching staff. Where engagements of these sorts are described as beneficial to learning, students self-report that they adopt deeper approaches to learning, with the strongest correlations being between approach to learning and feelings of benefit derived from being in contact with active researchers. This result, from a student perspective, is a significant contribution to the debate on teaching–research relations in higher education within and beyond Oxford University as it bypasses teaching and focuses on the more important relations between university research and student learning.  相似文献   

Distribution of<Emphasis Type="Italic">H. pylori</Emphasis> antigens in gastric mucosa and its significance     

Lu?Xin-liangEmail author  Qian?Ke-da  Tang?Xun-qiu  Zhu?Yong-liang 《浙江大学学报(A卷英文版)》2004,5(2):242-245

Objective: To investigate the distribution ofH. pylori antigens in the gastric mucosa in patients withH. pylori infection, and the relationship between the distribution and gastric cancer. Methods: Of 112 patients confirmed by pathological study to have chronic superficial gastritis, precancerous changes (chronic atrophic gastritis, intestinal metaplasia or atypical hyperplasia) and gastric cancer, 28 wereH. pylori negative and 84 wereH. pylori positive.H. pylori antigens in the gastric mucosa were detected by immunohistochemistry. Results: TheH. pylori positive group, comprised 12 of 22 (50.0%) in the chronic superficial gastritis group, 22 of 25 (88.0%) in the precancerous changes group and 13 of 35 (37.1%) in the gastric cancer group. The positive rates ofH. pylori antigens in the cytoplasm progressively increased, respectively at 0.0% (0/12), 63.6% (14/22) and 84.6% (11/13) for the same groups (χ ²=19.76,P=0.000);H. pylori antigens were located in the mucus layer and above the neck of the mucosal gland in 9 of 12 (75.0%) cases with chronic superficial gastritis, at the neck of the mucosal gland and the isthmus in 12 of 22 (54.5%) cases with precancerous changes, below the isthmus in 9 of 13 (69.2%) cases with gastric cancer (χ ²=25.30,P=0.000). In theH. pylori negative group, noH. pylori antigen was observed. Conclusion: With the progression of chronic superficial gastritis→precancerous changes→gastric cancer,H. pylori antigens progressively migrated from the outer part to the inner part of the cell, and from the superficial to the deep gastric mucosa.  相似文献   

Relations between student learning patterns and personal and contextual factors and academic performance     

Jan?D.?VermuntEmail author 《Higher Education》2005,49(3):205-234

This study was aimed at clarifying relations between the way students learn and personal, contextual and performance variables. Students from seven different academic disciplines completed the Inventory of Learning Styles (ILS). Besides, data about their age, gender, academic discipline, prior education and exam performance were gathered. Regression and correlations analyses were used to analyse the data. The results showed that students learning patterns were indeed associated with personal and contextual factors such as academic discipline, prior education, age and gender, but that the different learning patterns had different sources. Second, students learning patterns proved to explain an important part of the variance in their academic performance. However, the results also revealed that exams as usually used in the first years of higher education hardly capitalise on students use of critical, analytical and concrete processing strategies.  相似文献   

Including students’ diverse perspectives on classroom interactions into video-based professional development for teachers     

Anna-Marietha?Vogler  Susanne?PredigerEmail authorView author&#;s OrcID profile 《Journal of Mathematics Teacher Education》2017,20(5):497-513

Video is often used in professional development courses to sensitize mathematics teachers to students’ thinking and issues of classroom interaction. This article presents an approach that incorporates students’ perspectives on mathematics classroom interactions into video-based professional development in order to enhance teachers’ reflection on diverse awareness of students concerning demands within mathematics classroom interactions. This approach is theoretically justified by the empirical research on equal participation in classroom interaction and practically elaborated by video material from Grade 5 students. Empirical snapshots from design experiments with teachers demonstrate that teachers’ sensitivity can be enhanced.  相似文献   

多媒体课件的表达策略设计     

谢玉华  田思  杨玲玲 《滨州学院学报》2003,19(2):80-83

表达策略设计是多媒体课件设计的一个重要环节,主要包括视听表达的心理策略设计、视听素材组接的策略设计、人机交互界面的策略设计等方面.  相似文献   

Stimulus specificity of concurrent recovery in the rabbit nictitating membrane response     

Weidemann G  Kehoe EJ 《Learning & behavior》2005,33(3):343-362

Three experiments demonstrated that, following the extinction of an established conditioned stimulus (CS; e.g., tone), the pairing of an orthogonal stimulus from another modality (e.g., light) with the unconditioned stimulus (US) results in strong recovery of responding to the extinguished CS. This recovery occurred to about an equal degree regardless of whether or not initial training contained unambiguous stimulus—reinforcer relationships—that is, consistent CS—US pairings—or some degree of ambiguity, including intramodal discrimination training, partial reinforcement, or even cross-modal discrimination training (tone vs. light). Experiments 1 and 2 demonstrated that this recovery of responding was largely specific to the extinguished CS, but moderate generalization to other stimuli from the same modality did appear. The results are discussed with reference to alternative mechanisms applicable to learning-dependent generalization between otherwise distinct CSs. These models assume that such generalization is mediated by either a shared response, shared reinforcer, shared context, or shared hidden units within a layered neural network. A specific layered network is proposed to explain the present results as well as other types of savings seen previously in conditioning of the rabbit nictitating membrane response.  相似文献   

Toulmin’s argument pattern as a “horizon of possibilities” in the study of argumentation in science education     

Sibel?ErduranEmail authorView author&#;s OrcID profile 《Cultural Studies of Science Education》2018,13(4):1091-1099

Kim and Roth (this issue) purport to draw on the social-psychological theory of L. S. Vygotsky in order to investigate social relations in children’s argumentation in science topics. The authors argue that the argumentation framework offered by Stephen Toulmin is limited in addressing social relations. The authors thus criticize Toulmin’s Argument Pattern (TAP) as an analytical tool and propose to investigate the genesis of evidence-related practices (especially burden of proof) in second- and third-grade children by studying dialogical interactions. In this paper, I illustrate how Toulmin’s framework can contribute to (a) the study of “social relations”, and (b) provide an example utilizing a theoretical framework on social relations, namely Engeström’s Activity Theory framework, and (c) describe how we have used the Activity Theory along with TAP in order to understand the development of argumentation in the practices of science educators. Overall, I will argue that TAP is not inherently incapable of addressing social relational aspects of argumentation in science education but rather that science education researchers can transform theoretical tools such as Toulmin’s framework intended for other purposes for use in science education research.  相似文献   

The Effects of Role Congruence and Role Conflict on Work,Marital, and Life Satisfaction     

Kristin?M.?PerroneEmail author  L.?Kay?Webb  Rachel?H.?Blalock 《Journal of Career Development》2005,31(4):225-238

The impact of role congruence and role conflict on work, marital, and life satisfaction was studied using Super’s life-span, life-space theory. A conceptual model of relationships between these variables was proposed, and gender differences were examined. Participants were 35 male and 60 female college graduates who completed surveys by mail. Results indicated adequate fit for the proposed model. Results of gender analyses indicated that women in this study participated more in parenting and housework, whereas men participated more in career and leisure activities. Despite the differences in actual role participation, no gender differences were found regarding ideal role participation. Both men and women reported that the parent role was most rewarding. Implications for counselors and directions for future research were discussed.  相似文献